There isn't one specific scientific term for "sky". It's a more general term used to describe what we see when we look up.

Here are some scientific terms that describe aspects of what we see as "sky":

* Atmosphere: The layer of gases surrounding the Earth. This is where the weather happens and where we see the clouds.

* Troposphere: The lowest layer of the atmosphere, where most weather occurs.

* Stratosphere: The layer above the troposphere, containing the ozone layer.

* Mesosphere: The layer above the stratosphere, where most meteors burn up.

* Thermosphere: The layer above the mesosphere, characterized by very high temperatures.

* Exosphere: The outermost layer of the atmosphere, gradually fading into space.

The appearance of the sky can be described using terms like:

* Blue sky: The scattering of sunlight by air molecules (Rayleigh scattering).

* Cloudy sky: The presence of clouds, which can be described by their type (e.g., cumulus, stratus, cirrus).

* Sunset/sunrise: The change in color of the sky due to the angle of the sun's rays.

So, depending on what aspect of the "sky" you are interested in, different scientific terms would be appropriate.